1. Field of the Invention
The present invention relates to devices for charging electrical equipment, such as cellular telephones, computers, personal music players and the like.
2. Description of the Prior Art
Electronic devices, including cellular telephones and personal electronic devices, such as the iPad™ and iPod™ products, require device specific chargers to recharge their internal batteries. For example, some devices require a 2.1 ampere current to recharge, while others require a one (1) ampere current. As such, chargers are frequently not interchangeable, requiring each electronic device to have a specific charger.
Many electronic devices utilize a USB (universal serial bus) connector and cable to charge their internal batteries. When the charger is connected to the electronic device, the device senses the capabilities of the charger connected thereto by determining the voltage at the D+ and D− pins on the USB connector. Charging devices commonly set the D+ and D− pins of their connectors to specific relative values to indicate the capabilities of the charger. For example, a charger in which the D+ pin is set to a relative low of 2 volts and the D− pin is set to a relative high of 2.7 volts would be indicating that it is capable of charging at a relatively low current, such as 1 ampere. Similarly, a charger in which the D+ pin is set to a relative high of 2.7 volts and the D− pin is set to a relative low of 2 volts would be indicating that it is capable of charging at a relatively high current, such as 2.1 amperes. If the device determines that the charger is only capable of supplying an inappropriate current, the device may not be compatible with the charger and may not accept the charge. For example, an iPod™ device usually requires a charger that supplies a 1 ampere current. If an iPod™ device is connected to a charger that identifies itself by the relative voltages on the D+ and D− pins as being capable of supplying a 2.1 ampere current, the iPod™ device may not accept the charge. As such, it is necessary for a user to use device-specific chargers to charge personal electronic devices. To overcome this problem, some universal chargers have two USB connectors for charging at either 2.1 amperes on one connector or 1 ampere on the other connector.
The present invention provides a novel charging device that overcomes the inherent disadvantages of the conventional charging devices.